Negaim 7:5-8:1

Negaim 7:5

If a person had a white spot and it got removed, he is ritually clean; If he removed it intentionally, Rabbi Eliezer says he is only purified after developing another nega from which he is purified. The Sages say he can only be purified after it has spread over his entire body. If the white spot is on the tip of one’s foreskin, he may still be circumcised.

Negaim 8:1

If tzaraas (“leprosy,” but not really) breaks out all over on one who was ritually unclean, he is ritually clean; if the ends of his limbs revert to their pre-tzaraas condition, he becomes ritually unclean until the white spot shrinks to smaller than the size of a split bean. If tzaraas breaks out all over on one who was ritually clean, he is unclean; if the ends of his limbs revert to their pre-tzaraas condition, he remains ritually unclean until the white spot returns to its former size.